A Persona-based Modeling for Contextual Requirements Genaína Nunes Rodrigues 1 , Carlos Joel Tavares 1 , Naiara Watanabe 1 Carina Alves 2 Raian Ali 3 1 Department of Computer Science, University of Brasília, 2 Department of Computer Science, Federal University of Pernambuco 3 Department of Computer Science, Bournemouth University genaina@unb.br REFSQ 2018 March 20, 2018 Rodrigues et al. A Persona-based Modeling for Contextual Requirements 1
Introduction “A persona is a fictional character that represents a group of users of a given system and renders the product development more effective and accommodative to diversity” [Cooper, 2004]. ...and can add a human-centred facet to RE practice Rodrigues et al. A Persona-based Modeling for Contextual Requirements 2
A Persona Example Rodrigues et al. Figure : The characterisation of persona Mary Collins. A Persona-based Modeling for Contextual Requirements 3
Introduction Goal models (GM) provide the goals for which the system should be designed and a set of ways to reach those goals in prescriptive and pragmatic manners [Guimarães et al., 2015]. Contextual Goal Model (CGM) makes explicit presentation of the relationship between a goals and their achievement strategies and the context : “a partial state of the world in which the system operates and is relevant to its goals.” [Ali et al., 2010]. Rodrigues et al. A Persona-based Modeling for Contextual Requirements 4
A Goal Model Example respond to emergency Ambulance Dispatchin Mobile and g System Personal Emergency emergency is medical care Response detected reaches [p] Ch [p] is no)fied ambulance is or about emergency dispatched to [p] loca)on Ct Ct ^ Cha central or no)fies [p] receives [p] info centrals by mobile calls [p] [p] call for vibra)on and help is accepted [p] info is no)fies [p] no)fies [p] [p] info is sent situa)ons are prepared by light alert by sound alert to emergency and iden)fied receives or contact emergency and responsible for Ch v Ca ¬Ct ¬Ct buDon call or [p] processes iden)fies setup sensors data ¬Ct v Cha situa)on or Ch v Ca automated [p] send [p] info send [p] info info no)fy central (¬Ct v Cha) by SMS by internet get info from vital signs are responsible for [p] by SMS monitored and no)fy central by Internet [p] situa)on and [p] loca)on is data is collects data iden)fied recovered false alarm is persists data from sensors checked to database Cm or Cm v ¬Ct or acess data Consider last known access [p] loca)on from Cha ^ ¬Ct Cha ^ ¬Ct [l] from a GPS database loca)on [l] of [p] accepts [p] is contacted Cm v ¬Ct emergency Cha v ¬Ct access [p] loca)on [l] from iden)fies [p] confirms triangula)on loca)on [l] emergency by voice call by call Pa)ent contexts: Ch: Health risk Cm: Mobility issue Ct: Technology aversion Cha: Home assistance Ca: Physical ac)vity Figure : CGM’s Emergy Response in AAL (adapted from [Guimarães et al., 2015]) Rodrigues et al. A Persona-based Modeling for Contextual Requirements 5
Motivation Goals and capabilities are core and also shared constituents for both goal modelling and personas making the integration of power between both techniques easier and natural! Rodrigues et al. A Persona-based Modeling for Contextual Requirements 6
Problem In traditional GORE, people roles, responsibilities and permissions need to be normalized to fit in a general model. However, in reality people play different roles in different ways! And a case by case basis would add infeasible overhead to the engineers by personalizing the requirements [Sutcliffe et al., 2005]. Rodrigues et al. A Persona-based Modeling for Contextual Requirements 7
A Persona-based Modelling for Contextual Requirements How can we empower GORE modelling practice with personalization and human-centred design facets? In addition, how to devise a goal achievement sensitive to their actual set of personas? Rodrigues et al. A Persona-based Modeling for Contextual Requirements 8
Persona Attribute Formalization We formalize the description of the persona attributes into contextual facts as follows: 1 i is the id of the persona in the population of interest. 2 A i ∈ { A 1 , A 2 ,..., A n }, where A is a set of attributes as nominal categorical variables of i . 3 Each attribute A i may have a corresponding contextual fact F j , where i ≤ j . j 4 i = � F n , the persona i is characterized as the union of F j n = 1 contextual facts. Rodrigues et al. A Persona-based Modeling for Contextual Requirements 9
The Personas Contexts Context as a predicate formula of and/or combinations of statements and facts [Ali et al., 2010]. Contextual facts in our work map only those relevant and verifiable persona information. Rodrigues et al. A Persona-based Modeling for Contextual Requirements 10
Structuring the Contextual Facts into Contexts Ch w1=[p] has degree of health status f1= [p] has f3= [p] is f5= [p] is prone diabetes f6= [p] has cardiac to falling osteoporosis f2= [p] has f4= [p] has HBP rheumatoid f9 = [p] is f7 = [p] is low critical high critical Legend FACT Statement f8 = [p] is OR AND Imply Support medium critical Figure : Excerpt of the Health Context Structure. Rodrigues et al. A Persona-based Modeling for Contextual Requirements 11
Formalization of a Persona’s Context Set Definition (Persona Context Set) Cj Let the mapping function C : i → {T, F} which returns true or false for − the facts of persona i applied to context C j . If C j ( i ) = T, it means that C j ∈ Ω , where Ω is the set of contexts triggered by persona i . Rodrigues et al. A Persona-based Modeling for Contextual Requirements 12
A Context Set Example Based on the Persona Mary Collins attributes and goals, Mary’s context set follows: Facts: (F1,F5,F6,F14,F19) Health Context (Ch): (F1 & F5 & F6) Home Assistance (Cha): (F14) Technology Aversion (Ct): (F19) Therefore, Mary’s Context Set = {Ch, Cha, Ct} Rodrigues et al. A Persona-based Modeling for Contextual Requirements 13
The Relationship Between Actors and Persona Goals C1 Persona Persona:P1 Goal Actor Persona Actor Goal Goal Persona:P2 C2 Persona Goal C3 Persona:P3 Rodrigues et al. A Persona-based Modeling for Contextual Requirements 14
Achievability of a Persona Goal Satisfaction Definition (Persona Goal Satisfaction) Let the context set Ω triggered by persona i , the actor goal Γ , which the persona goal is link dependent, and the target system CGM. The persona goal satisfaction property Φ i is achieved when ( Ω , Γ , CGM) � Φ i Rodrigues et al. A Persona-based Modeling for Contextual Requirements 15
Goal Achievement Check Persona goal satisfaction via the goal achievement check algorithm (further details on the paper). CGM goals achievability facing personas context sets. Enables richer adaptation decisions for: Achievability analysis in explicitly modelled user context The effect of the user context on a goal fulfillment criteria Rodrigues et al. A Persona-based Modeling for Contextual Requirements 16
Goal Achievement Check Persona goal satisfaction via the goal achievement check algorithm (further details on the paper). CGM goals achievability facing personas context sets. Enables richer adaptation decisions for: Achievability analysis in explicitly modelled user context The effect of the user context on a goal fulfillment criteria The achievability of a goal is a selection and enactment of a suitable alternative to reach a goal under a certain or multiple persona contexts criteria. Rodrigues et al. A Persona-based Modeling for Contextual Requirements 16
Feasibility Study on MPERS 19 distinctive facts for the considered personas. Eight distinctive contexts: five for the patients and three for the medical doctor. Four modelled personas: 3 patients and 1 doctor Rodrigues et al. A Persona-based Modeling for Contextual Requirements 17
Feasibility Study on MPERS – The GQM Table : GQM devised plan Goal: Analysis of the achievability of the goals Question Metric Q1. Is the algorithm efficient to come up Execution time with an execution plan? Q2. Does the algorithm allow testing Yes/No and explaining persona-based goal achievability? Q3. Are the plans provided by the % of correct algorithm correct? plans Rodrigues et al. A Persona-based Modeling for Contextual Requirements 18
Results Q1 - Is the algorithm efficient to come up with an execution plan? Algorithm’s complexity for the goal achievement check is linear on time (further details on the paper). Q2 - Does the algorithm allow testing and explaining persona-based goal achievability? Only Mary did not have the MPERS goals achieved! Mary has technology aversion to some degree since she fears having frustrating experiences with technology. Rodrigues et al. A Persona-based Modeling for Contextual Requirements 19
Results Q3. Are the plans provided by the algorithm correct? Planning 1 Consider last Notify Notifies [p] Ambulance known location central by by mobile Dispatching [i] of [p] SMS vibration System Send [p] Access Accepts info by data from emergency SMS database Identifies [p] location [i] by voice call Planning 2 Figure : Achievable Plans for the provided personas contexts. Rodrigues et al. A Persona-based Modeling for Contextual Requirements 20
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